1. Field of the Invention
The present invention relates to a network status indicating circuit, and particularly to a network status indicating circuit compatible with different types of network ICs.
2. Description of Related Art
There are two types of network status indicating circuit using indicating units such as LEDs: 1) a first type of network status indicating circuit indicates the networks according to the combination of two status signals designated Speed and Link, 2) a second type of network status indicating circuit indicates the network status according to two status signals independent from each other designated 10 M/LINK/ACTIVITY and 100 M/LINK/ACTIVITY. Referring to FIG. 2, the first type of indicating circuit includes a first type of network IC 10, a NOT gate U1, two LEDs L1, L2, and a resistor Ra. The network IC 10 includes a Speed pin connected to an anode of the LED L1 and an input terminal of a NOT gate. An output terminal of the NOT gate is connected to an anode of the LED L2. A node A between two cathodes of the two LEDs L1, L2 is connected to a Link pin of the network IC 10 through the resistor Ra. The NOT gate U1, the two LEDs L1, L2 and the resistor Ra constitute an indicator circuit. The network IC 10 is set in a kernel board, and the indicator circuit is set in a device board.
Level/value of the Link pin corresponding to the network status, and level/value of the Speed pin corresponding to the network transmitting speed are listed below:
TABLE 1Network statusLevel/value of Link pinLinkedLow/0Not linkedHigh/1Transmitting and ReceivingAlternating between 0, 1
TABLE 2Network transmitting speedLevel/value of Speed pin 10 MbpsHigh/1100 MbpsLow/0According to Table 1, value at the Link pin is 0 when the network is “linked”, and is 1 when the network is “not linked”. When the network is “transmitting and receiving”, the value at the Link pin alternates between 0 and 1. According to Table 2, the value at the Speed pin is 1 when the speed of the network is 10 Mbps, and is 0 when the speed of the network is 100 Mbps. So when the network speed is 10 Mbps and the network is “linked”, the LED L1 lights up. When the network speed is 100 Mbps and the network is “linked”, the LED L2 lights up. When the network speed is 10 Mbps and the network is “transmitting and receiving”, the LED L1 blinks. When the network speed is 100 Mbps and the network is “transmitting and receiving”, the LED L2 blinks. When the network is “not linked”, the two LEDs L1 and L2 remain off.
Referring to FIG. 3, the second type of indicating circuit includes a second type of network IC 20, two resistors Rb, Rc, and two LEDs L3, L4. A 10 M/LINK/ACTIVITY pin of the network IC 20 is connected to an anode of the LED L3 through the resistor Rb, and a 100 M/LINK/ACTIVITY pin of the network IC 20 is connected to an anode of the LED L4 through the resistor Rc. Cathodes of the two LEDs L3 and L4 are grounded. The two resistors Rb and Rc, the two LEDs L3 and L4 constitute an indicator circuit. The network IC 20 is set in a kernel board, and the indicator circuit is set in a device board. When the network speed is 10 Mbps and the network is “linked”, the LED L3 lights up. When the network speed is 100 Mbps and the network is “linked”, the LED L4 lights up. When the network speed is 10 Mbps and the network is “transmitting and receiving”, the LED L3 blinks. When the network speed is 100 Mbps and the network is “transmitting and receiving”, the LED L4 blinks. When the network is “not linked”, the two LEDs L3, L4 remain off.
According to the FIGS. 2 and 3, a network status indicating circuit is only compatible with a specified network IC, so different indicator circuits are needed corresponding to different network ICs. Sometimes the network IC in the kernel board must be exchanged for a different type, and so the indicator circuit in the device board must also be changed in accordance with the new network IC.
What is needed, therefore, is a network status indicating circuit which can solve the above the problem.